1. Field of the Invention
The present invention relates to a manufacturing method of a thermally-assisted magnetic write head for use of thermally-assisted magnetic writing with which writing of information is performed by reducing the coercive force of a magnetic recording medium through irradiation of a near-field light.
2. Description of the Related Art
A magnetic disk device has been previously used for recording and reading of magnetic information (hereinafter, simply referred to as information). The magnetic disk device is the one provided with a magnetic disk and a magnetic write/read head inside of a chassis, for example. The magnetic disk stores therein information, and the magnetic write/read head performs recording of information to this magnetic disk, and performs reproduction of the information recorded on the magnetic disk. The magnetic disk is supported by the rotation shaft of a spindle motor that is fixed to the chassis, and is so configured as to rotate thereabout. On the other hand, the magnetic write/read head is formed to one side surface of a magnetic head slider that is disposed at one end of a suspension, and is so configured as to include a magnetic recording element and a magnetic read element that are each provided with an air bearing surface (ABS; Air Bearing Surface) opposing the magnetic disk. Especially, as the magnetic read element, an MR element producing the magnetoresistive (MR: Magnetoresistive) effects is generally used. The remaining end of the suspension is attached to the tip end of an arm that is supported to the fixed shaft to be able to pivot thereabout. The fixed shaft is the one disposed upright in the chassis.
When the magnetic disk device is in the resting state, that is, when the magnetic disk is not moving with no rotation, the magnetic write/read head does not exist on the magnetic disk, and is in the state of being out of the way toward the outside (in the state of unloading). In such a state, when the magnetic disk device is put in the driving state, and when the magnetic disk starts rotating, the magnetic write/read head is put in the state of being moved to a predetermined position on the magnetic disk together with the suspension (in the loaded state). When the rotation of the magnetic disk reaches any predetermined rotation speed, the balance between the positive pressure and the negative pressure makes the magnetic head slider suspended with a good stability with a slight distance from the surface of the magnetic disk so that the recording and reproduction of information may be performed with a good accuracy.
In recent years, a magnetic disk has been increased in recording density (increased in capacity), and in response thereto, there has been a demand for the better performance capabilities of a magnetic write/read head and those of the magnetic disk. The magnetic disk is a non-contiguous medium being a cluster of magnetic particles, and the magnetic particles are each in the single-domain structure. In such a magnetic disk, one recording bit is configured by a plurality of magnetic particles. These magnetic particles are required to be smaller in size because, for the purpose of increasing the recording density, the border between any two recording bits adjacent to each other has to be less bumpy. However, if the magnetic particles are reduced in size as such, the resulting decrease of volume of the magnetic particles causes a problem of reducing the thermal stability in terms of magnetization of the magnetic particles. In order to solve such a problem, increasing the anisotropic energy of the magnetic particles produces good effects. The concern here is that, however, if the anisotropic energy of the magnetic particles is increased as such, the magnetic disk is resultantly increased in coercive force, thereby causing a problem of difficulty in information recording for any existing magnetic head.
As a method for solving such problems as described above, a method of so-called thermally-assisted magnetic writing has been proposed. This method uses a magnetic recording medium with a higher degree of coercive force, and during recording of information, a portion of the magnetic recording medium for recording of information is heated at the same time as the application of a magnetic field. As such, the portion is increased in temperature but is reduced in coercive force, thereby performing the recording of information. Hereinafter, the magnetic head for use with the thermally-assisted magnetic writing as such is referred to as thermally-assisted magnetic write head. Note here that as to the thermally-assisted magnetic write head, the one in Specification of United States Patent Application No. 2007/139818 or the one in Specification of United States Patent Application No. 2009/168220 is known.
With such thermally-assisted magnetic writing, as a method for applying heat to a magnetic recording medium, a method of using a near-field light is generally used. As a method of generating such a near-field light, a generally known method is to use a near-field light probe, i.e., so-called plasmon generator. The near-field light probe is a metal piece that generates a near-field light from plasmons excited by a light. The concern here is that, however, a material mainly including Au (gold), Ag (silver), Cu (copper), Al (aluminum), or others those considered each as a preferable material to configure the plasmon generator that generates a near-field light through irradiation of a light has the characteristics of being easily removed by a process of etching (ion beam etching or others) that is generally executed for the purpose of removing any impurities during the formation of an air bearing surface. Therefore, in the air bearing surface, the end surface of the plasmon generator shows a tendency to be in the state of being positioned in the rear of the end surface of a magnetic pole, that of a waveguide, or that of a shield layer, for example. Accordingly, with the thermally-assisted magnetic write head in such a state, during the operation thereof, the near-field light may not be enough in intensity, or the write head may not be stable enough while it is in the state of being suspended, and this is considered not desirable in view of reliability.
In consideration thereof, the air bearing surface is expected to be better in flatness, and the operation capabilities are expected to be provided with a better stability.